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Vulnerability record · CVE-2026-45389 · published 15 June 2026

CVE-2026-45389: Improper certificate validation vulnerability

In OCaml-TLS before 2.1.0, the server implementation does insufficient checks of the certificate provided by the client (when doing client authentication), which allows impersonation with certificates that are not meant for client authentication (because of KeyUsage and ExtendedKeyUsage).

7.4 CVSS 3.1 High EPSS 0.25% · top 85.7% CWE-295 · Improper certificate validation Deferred
7.4CVSS 3.1 base score
0.25%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
1References
17 Jun 2026Last modified by NVD

Description

In OCaml-TLS before 2.1.0, the server implementation does insufficient checks of the certificate provided by the client (when doing client authentication), which allows impersonation with certificates that are not meant for client authentication (because of KeyUsage and ExtendedKeyUsage).

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

References

LinkTags
https://osv.dev/vulnerability/OSEC-2026-07

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Source: NIST National Vulnerability Database (record CVE-2026-45389), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.